Definition/General
Introduction:
Kimura disease is a rare chronic inflammatory disorder characterized by eosinophil-rich lymphadenopathy and subcutaneous nodules
First described by Kim and Szeto in 1937, later detailed by Kimura in 1948
It predominantly affects young Asian males
FNAC shows characteristic eosinophil-rich inflammatory infiltrate with distinctive morphological features.
Origin:
Etiology remains unclear but likely involves allergic or autoimmune mechanisms
Type 2 immune response with Th2 cell activation
IgE-mediated hypersensitivity may play a role
Results in eosinophil recruitment and tissue infiltration
Angiogenesis and fibrosis are secondary features
Chronic inflammatory response to unknown antigen.
Classification:
Clinical classification: Localized disease (single site involvement)
Regional disease (multiple sites in same region)
Systemic disease (rare)
Morphological patterns: Eosinophil-rich type (classic pattern)
Lymphoid hyperplasia type
Fibrotic type (chronic phase)
IgG4-related variant (recently described).
Epidemiology:
Predominant in East Asian populations (Chinese, Japanese, Korean)
Male predominance (male:female = 3-4:1)
Peak incidence in 2nd-4th decades (20-40 years)
Rare in Western populations
Endemic in certain geographic regions
Familial clustering occasionally reported.
Clinical Features
Presentation:
Unilateral cervical lymphadenopathy (most common)
Subcutaneous nodules in head and neck region
Parotid gland involvement (40-50% cases)
Pruritic skin lesions
Slowly progressive course
Painless masses typically
Recurrent episodes common.
Symptoms:
Pruritus (intense itching) in 60-70% patients
Local discomfort due to mass effect
Cosmetic concerns due to visible nodules
Renal symptoms (proteinuria, hematuria) in 10-20%
Constitutional symptoms rare
Allergic symptoms (rhinitis, asthma) occasionally
Weight loss uncommon.
Risk Factors:
Asian ethnicity (major risk factor)
Male gender
Young adult age
Allergic predisposition
Atopic constitution
Environmental factors possible
Genetic susceptibility
Geographic location (East Asia).
Screening:
No specific screening available
Complete blood count shows eosinophilia (80-90% cases)
Elevated serum IgE levels (>1000 IU/mL in 70% cases)
Elevated eosinophil count (>500/μL)
Renal function tests (proteinuria possible)
Complement levels may be low
Allergic workup (skin prick tests).
Master Kimura Disease FNAC Pathology with RxDx
Access 100+ pathology videos and expert guidance with the RxDx app
Gross Description
Appearance:
Enlarged lymph nodes (typically 2-8 cm)
Nodes are firm and mobile
Subcutaneous nodules may coexist
Cut surface shows tan-pink coloration
Homogeneous appearance typically
No necrosis usually
Increased vascularity may be noted.
Characteristics:
FNAC yields highly cellular material
Eosinophil-rich population characteristic
Mixed inflammatory infiltrate
Proteinaceous background
May be hemorrhagic due to increased vascularity
Abundant eosinophils in all fields
Reactive lymphoid cells present.
Size Location:
Cervical lymph nodes most commonly affected (80%)
Preauricular and submandibular regions frequent
Parotid gland involvement common
Axillary nodes less frequent
Node size ranges from 1-10 cm
Unilateral involvement typical initially.
Multifocality:
Regional clustering of affected nodes
Unilateral involvement initially, may become bilateral
Subcutaneous nodules often coexist
Parotid gland masses frequent association
Progressive involvement of adjacent areas
Recurrence at same or nearby sites common.
Microscopic Description
Histological Features:
FNAC shows abundant eosinophils (>20% of nucleated cells)
Reactive lymphoid hyperplasia with follicle formation
Increased vascularity with endothelial proliferation
Fibroblast proliferation in chronic cases
Plasma cells and mast cells present
Proteinaceous exudate in background.
Cellular Characteristics:
Eosinophils: Abundant mature eosinophils with bilobed nuclei, eosinophilic granular cytoplasm
Lymphocytes: Mixed population with immunoblasts and transformed lymphocytes
Plasma cells: Polyclonal population, Russell bodies may be present
Endothelial cells: Plump, activated appearance
Fibroblasts: Spindle-shaped cells in chronic lesions
Mast cells: Scattered throughout.
Architectural Patterns:
Follicular hyperplasia with germinal center formation
Interfollicular eosinophil infiltration
Increased vascularity with capillary proliferation
Subcapsular eosinophil collections
Fibrosis in chronic cases
Preservation of nodal architecture initially.
Grading Criteria:
No formal grading system for Kimura disease
Assessment based on eosinophil density
Degree of fibrosis
Vascular proliferation extent
Follicular hyperplasia degree
Chronicity features (sclerosis, hyalinization)
Clinical correlation for disease activity.
Immunohistochemistry
Positive Markers:
CD3 positive in T-lymphocytes
CD20 positive in B-lymphocytes (follicles)
CD68 positive in macrophages
Tryptase positive in mast cells
CD34 highlights increased vascularity
IgE positive in plasma cells
IgG4 positive in subset (IgG4-related variant).
Negative Markers:
Cytokeratin negative (excludes carcinoma)
CD30 and CD15 negative (excludes Hodgkin lymphoma)
ALK negative (excludes ALCL)
S-100 negative in eosinophils
Langerin negative (excludes LCH)
CD1a negative (excludes LCH).
Diagnostic Utility:
IHC has limited diagnostic utility for Kimura disease
Mainly used to exclude other conditions
IgE and IgG4 staining may support diagnosis
Helps confirm polyclonal nature of lymphoid infiltrate
CD34 staining highlights increased vascularity
Useful in differential diagnosis with lymphoma.
Molecular Subtypes:
Kimura disease shows Th2-polarized immune response
High IL-4, IL-5, IL-13 levels
IgE class switching
Eosinophil chemotaxis factors elevated
VEGF upregulation (explains increased vascularity)
IgG4-related subset with distinct features.
Molecular/Genetic
Genetic Mutations:
No specific genetic mutations identified for Kimura disease
HLA associations reported in some populations
Cytokine gene polymorphisms may influence susceptibility
IgE receptor polymorphisms
Complement gene variants
No clonal gene rearrangements
Reactive polyclonal process.
Molecular Markers:
Elevated serum IgE (often >1000 IU/mL)
Peripheral blood eosinophilia (>500/μL)
Elevated IL-5 levels
High eotaxin levels
Increased TARC levels
Complement consumption (low C3, C4)
Normal immunoglobulin gene rearrangements.
Prognostic Significance:
Benign chronic condition with good overall prognosis
Recurrent course common (60-70% patients)
No malignant potential
Renal involvement may affect prognosis (10-20% cases)
Complete spontaneous remission rare
Response to treatment variable
Long-term follow-up required.
Therapeutic Targets:
Corticosteroids: First-line treatment (prednisone)
Surgical excision: For localized disease
Radiotherapy: For recurrent disease
Immunosuppressants: Methotrexate, azathioprine
Anti-IgE therapy: Omalizumab (experimental)
Cyclosporine: For refractory cases
Antihistamines: For symptomatic relief.
Differential Diagnosis
Similar Entities:
Angiolymphoid hyperplasia with eosinophilia (ALHE)
Hypereosinophilic syndrome
Hodgkin lymphoma with eosinophilia
Parasitic infections
Allergic reactions
Drug-induced eosinophilia
Eosinophilic granulomatosis with polyangiitis
Lymphoma with eosinophilia.
Distinguishing Features:
ALHE: More superficial, prominent vascular proliferation, different demographics
Hypereosinophilic syndrome: Systemic organ involvement, higher eosinophil counts
Hodgkin lymphoma: Reed-Sternberg cells, CD15/CD30 positive
Parasitic infections: Organisms identifiable, different clinical context
Drug-induced: Drug history, resolution after withdrawal.
Diagnostic Challenges:
Distinguishing from ALHE (closely related condition)
Secondary eosinophilia from other causes
Reactive eosinophilic infiltrates
IgG4-related disease with eosinophilia
Atypical presentations
Mixed patterns with other inflammatory conditions.
Rare Variants:
IgG4-related Kimura disease
Systemic Kimura disease with multi-organ involvement
Kimura disease with nephrotic syndrome
Recurrent/refractory Kimura disease
Pediatric Kimura disease
Kimura disease with malignancy (rare association).
Sample Pathology Report
Template Format
Sample Pathology Report
Complete Report: This is an example of how the final pathology report should be structured for this condition.
Specimen Information
Fine needle aspiration cytology of [site] lymph node/mass
Clinical History
Age: [age], Gender: [gender], Ethnicity: [Asian/other]. Clinical presentation: [lymphadenopathy/subcutaneous nodule]. Duration: [duration]
Adequacy
Adequate for evaluation - highly cellular smears with abundant inflammatory cells
Morphological Features
Highly cellular smears showing abundant eosinophils (>20% of nucleated cells). Reactive lymphoid hyperplasia with immunoblasts and transformed lymphocytes. Increased vascularity. Mixed inflammatory infiltrate
Eosinophil Component
Abundant mature eosinophils with characteristic bilobed nuclei and eosinophilic granular cytoplasm. Estimated percentage: [X]% of nucleated cells
Laboratory Correlation
Peripheral blood eosinophilia: [present/absent]. Serum IgE levels: [elevated/normal]. Total eosinophil count: [count]/μL
Cytological Diagnosis
Eosinophil-rich lymphadenopathy, consistent with Kimura disease
Recommendations
Clinical correlation advised. Complete blood count with eosinophil count. Serum IgE levels. Renal function assessment. Dermatology/Hematology consultation as indicated
Comments
The presence of abundant eosinophils in the appropriate clinical setting (young Asian male with lymphadenopathy) is consistent with Kimura disease. This is a benign chronic inflammatory condition